Reciprocating compressor apparatus



E. T; NEUBAUER REICIPROCATING COMPRESSOR APPARATUS Filed Sept. 15, 1.954

Jan '-20,

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DISCH E EM/L 7 NEUB R m v w NEY 2,869,775 RECIPROCATING CQMPRESSOR APPARATUS Emil T. Neuhauer, La (Irosse, Wis, assignor to The Trane Company, La (Irosse, Wis, a corporation oi Wisconsin This invention relates to reciprocating compressors of general utility such as air compressors and particularly refrigeration compressors in which the loss of oilfrom the crankcase on starting is prevented and the circulation of oil through the crankcase during operation is kept at a minimum.

On starting reciprocating compressors which use refrigerant 12 namely dichlorodifiuoromethane, refrigerant 22 namely monochlorodifluoromethane, or other refrigerants miscible with the lubricating oil, there is a substantial loss of oil from the crankcase due to foaming, with the result that there is an insuflicient supply of oil for proper lubrication of the operating parts. The oil which is carried from the compressor by the refrigerant goes into the refrigeration system and greatly reduces the efliciency of the heat exchangers in the system.

it is an object of the present invention to provide a compressor in which these disadvantages are eliminated or reduced to a practical minimum.

It is an object of this invention to provide a compressor in which the loss of oil into the refrigeration system during starting of the compressor is reduced to a practical minimum.

It is a further object of thisinventio-n to provide a compressor having means for separating the lubricant from the foam of lubricant and refrigerant and to return the lubricant to the crankcase.

It is another object of the invention to provide means for maintaining in the crankcase an average pressure which is equal to or less than the average pressure in the suction chamber during operation of the compressor.

It is still another object of this invention to provide means for operating two or more compressors in parallel in a system with means for maintaining oil in the operating compressor when one or more of the compressors is not in operation.

Other objects and advantages will become apparent from the following description with reference to the accompanying drawings in which:

Fig. 1 is an end view of the compressor of this invention;

Fig. 2 is a diagrammatic view of a system having two compressors connected in parallel;

Fig. 3 is a view partly in elevation and partly in section taken substantially on line 3-3 of Fig. 1;

Fig. 4 is a fragmentary sectional view taken on line 33 of Fig. land showing a modification of the invention shown in Fig. 3;

Fig. 5 is a view in elevation of the foam breaker retaining plate;

Fig. 6 is an end view of the foam breaker retaining plate;

Fig. 7 is an end view of the check valve; and

Fig. 8 is a sectional view of the check valve taken on line 88 of Fig. 7.

Referring to the drawings and particularly Figures 1 and v3, the compressor has a body 10. The body 10 has at one end a flange 12 which is adapted to be secured to a prime mover such as an internal combustion engine or electric motor. The other end of the body is closed by a cover plate 14 which is bolted to the body 10. A hearing bracket 16 is supported in the body 10 and is held in position by cover it; which is bolted to the body 10. Bearing bracket 16 rotatably supports crankshaft Ztl. Cylinder liners 22 are mounted in the body it). Cylinder heads 24 close the ends of the cylinders and are bolted or otherwise secured to the body 10. Pistons 26 reciprocate in the cylinder liners 22. The pistons 26 are driven by connecting rods 28 which are mounted on the crankshaft 20. Each cylinder has a suction and discharge valve which are not shown because they are of an old and well known construction.

A bracket 30 is bolted to body 10 and supports oil pump 32 in driven engagement with crankshaft 2%. Pump 32 has a suction line 34 connected to a partially enclosed strainer 36.

The refrigerant gas enters the compressor through a suction valve 38 from which it flows to a suction chamber 40 from which it is manifolded to the cylinders. From the cylinders the compressed gas is conducted through passageways in the body 10 to a discharge valve 42. l

Gas can flow from the crankcase chamber 44 to the suction chamber 30 through check valve 46. A foam breaker in the form of a fine wire screen 4-3 is supported in the path of the gas to the check valve 4-6. A plate 5'0 is secured to the body 10 by screws not. shown. The plate 50 holds the screen 48 in place and has a pair of openings 52 through which gas and foam may flow.

The check valve 46 is shown in detail. in Figures 7 and 8. it has a ball closure member 54 which is movable to and from closing position in front of orifice Movement of gas from the crankcase to the suction chamber opens valve 46, and a tendency for the gas to flow in the opposite direction immediately closes the valve 46. A spring retaining ring 58 engages in a groove in the valve body to hold the ball closure member 54- in the body of the valve.

At the lower end of the suction chamber t? is a check valve so which permits oil to flow from the suction chamber to the crankcase 44. Check valve 60 immediately closes when there is a tendency for gas or foam to flow from the crankcase 44 to the suction chamber as. The check valve 60 is similar in construction to the check valve 46 except that the diameter of its orifice is less than that of orifice 56 of check valve 46. I prefer that the orifice 56 shall have a diameter greater than that of the orifice of check valve 60.

The manner in which the check valves 46 and so maintain a lower average pressure in the crankcase than in the suction chamber will now be described. Since the cylinders are not uniformly angularly spaced about the axis of the compressor the gas in the crankcase is compressed on each downstroke of the pistons. This causes gas to flow from the crankcase i l to the suction chamber 40 through the check valve 46. On the upstroke of the pistons the pressure is reduced in the crankcase and there is a tendency for gas to flow into the crankcase through check valve 46 but check valve 46 immediately closes. During the upstrokeof the pistons, check valve 60 opens, but the flow into the 'crankcase through this valve is considerably less than the flow outwardly through valve 46 during the downstroke of the pistons because the orifice in valve 60 is smaller and because the fluid is more viscous being either oil or a mixture of oil and gas. Since the tendency for flow from the crankcase is greater than the tendency for flow into the crankcase, the average pressure in the crankcase is lower than that in the suction chamber.

Another form of my invention is shown in Figure 4. In this form of the invention the oil is conducted from the suction chamber 4% to the crankcase 44 by a tube 61 which extends downwardly from the suction chamber to a point below the surface of the oil in crankcase 44. Since the tube 61 extends below the surface of the oil in the crankcase it serves as a liquid seal which prevents gas from flowing from the crankcase 44 to suction chamber 40 and yet permits the oil to return from the suction chamber 40 to the crankcase 4-4. In the lower end of tube 61 is secured an orifice plate 63 which restricts the flow through tube 61 in the event that a condition of excessive foaming should occur in the crankcase.

The modification of the invention shown in Figure 4 will maintain a lower average pressure in the crankcase than in the suction chamber in a manner similar to the embodiment of Figure 3 described above.

The operation of the duplexed compressor system of Figure 2 will now be described. The two compressors are designated by numerals 62 and 62 respectively. A crankcase equalization pipe 64 connects the two crankcases 66 and 66' of compressors 62 and 62' respectively. A common suction pipe 68 has branches 70 and '75? leading to suction chambers 72 and 72' of compressors 62 and 62 respectively. Discharge chambers '74 and 74 are connected by branch pipes 76 and 76 respectively to a single discharge pipe 78. The check valves 8% and 80 in the upper portion of the suction chambers are shown diagrammatically, the details of their construction being shown by check valve 46 in Figure 3. The check valves 32 and 5?. at the lower end of the suction chamber are shown diagrammatically, the details of their construction being a town by check valve 69 in Figure 3.

Prior art duplex. compressor systems to my knowledge do not have anything similar to the check valves 80 and 89"; and such systems do not have the advantages obtained with the pr sent invention. in such prior art systems assuming compressor 62 to be operating at full load and compressor 2 to be shut oil, the suction chamber because there will be no refrigerant flow in suction line '70. Suction chamber 72- will operate below the static pressure of suction line 68 due to the pressure drop suction pipe 76. With the oil equalization line 64 wide openbetween the two crankcases, they will tend to equalize out at the same pressure. Since the pressure in suction chamber 72 is higher than the pressure in suction chamber 72, check valve 82 will open, and without check valve 8% ofthis invention, gas will flow from suction chamber 72' to crankcase chamber 66 through check valve 32 and opening 81 and thence through equalization line 64 to crankcase 66. The flow from crankcase 66 to suction chamber '72 will cause valve 82 to close, leaving: only the opening at St for passage into the suction chamber 72. Since the total area of opening 81' and check valve 82 between the suction chamber and the crankcase in compressor 62 is greater than the area of the check valve 85) from crankcase to suction chamber in compressor 66, it is reasonable to assume that pressure in crankcase 66 will be greater than that in suction chamber 72 and therefore in such prior art systems there will be a resistance to the return of oil will be at the pressure of suction line 68 The apparatus of this invention restricts the flow through "check valves 82 and 82 and provides check valves 80 and 80 of greater capacity in the reverse direction. 7

Assuming again that compressor 62 is operating and that compressor 62' is shut off, the pressures in the suction lines will be the same as described above. Check valve 80' will close and check valve 82 will open. This will leave only restricted flow from suction chamber 72 to crankcase 66' and therefore a restricted flow through equalization line 64 into crankcase 66. Check valve 39 will open and check valve 82 will tend to close. Since check valve 80 has larger capacity flow than check valve 82, both crankcases can readily equalize to a pressure substantially equal to the lower pressure in suction chamber 72. With this condition established, a hydraulic pressure created by a small head of oil will open check valve 32 and permit the oil to flow back into the crankcase 66 of running compressor 62. If more than two compressors are operating in parallel in a system, the flow area of each valve 80, $0 and so on should be greater than the sum of the fiow areas of the valves 82, 82 and so on in the machines which could be idle during certain conditions of operation.

While I have described the preferred embodiments of my invention, 1 contemplate that many changes may be made without departing from the scope or spirit of my invention, and I desire to be limited only by the claims.

I claim:

1. A compressor comprising a housing, cylinders in said housing, reciprocating pistons operating in said cylinders, a partition in said housing dividing said housing into a crankcase and a suction chamber, first check valve means in said partition for conducting fluid from the crankcase to the suction chamber, and second check valve means in said partition for conducting fiuid'trcm the suction chamber to the crankcase, said first check valve means having a greater flow area than said second check valve means.

2. A multiple compressor system comprising a plurality of compressors, each of said compressors having a housing with partitions dividing the housing into a su:- tion chamber, a discharge chamber and a crankcase chamber extending below said suction chamber, a discharge conduit a first manifold in fluid communication with said discharge conduit and the discharge chambers of each of said compressors, a suction conduit a second manifold in fluid communication with said suction conduit and the suction chambers of each of said compressors, first check valve means in each compressor for conducting fluid from the crankcase chamber to the suction chamber, second check valve means in each compressor for conducting fluid from the suction chamber to the crankcase chamber, said first check valve means having a greater flow area than said second check valve means, and conduit connecting said crankcase chambers of each of said compressorsfor freely conducting fluid between said crankcase chambers.

References Cited in thefile of this patent UNITED STATES PATENTS 

